The best replacement for 5505 is sonicwall.

The best alternatives to 5505 are rated as following:
★★★★★  sonicwall
★★★★★  5510
★★★★  pix 501
★★★  pix 515e
★★  1841
★★  ssg 5
★★  881
  1921
  sa 540
  cisco asa 5510
  891

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Speaking about 5505, one probably shouldn't forget about dual isp.

Other search terms related to 5505 and their ratings are:
★★★★★ dual isp
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5505
sonicwall
5510